ahmetb/kubectx · error

failed to save kubeconfig file: %w

Error message

failed to save kubeconfig file: %w

What it means

clearNamespace wraps an error from kc.Save() as "failed to save kubeconfig file: %w". Save persists modified kubeconfig contents to disk; it fails on filesystem problems — missing directory, insufficient write permissions, disk full, or the file being replaced/locked concurrently.

Source

Thrown at cmd/kubens/unset.go:58

	err = printer.Success(stderr, "Active namespace is \"%s\".", printer.SuccessColor.Sprint(ns))
	return err
}

func clearNamespace(kc *kubeconfig.Kubeconfig) (string, error) {
	ctx, err := kc.GetCurrentContext()
	if err != nil {
		return "", fmt.Errorf("failed to get current context: %w", err)
	}
	ns := "default"
	if ctx == "" {
		return "", errors.New("current-context is not set")
	}

	if err := kc.SetNamespace(ctx, ns); err != nil {
		return "", fmt.Errorf("failed to clear namespace: %w", err)
	}
	if err := kc.Save(); err != nil {
		return "", fmt.Errorf("failed to save kubeconfig file: %w", err)
	}
	return ns, nil
}

View on GitHub (pinned to 12ad6fb22e)

Solutions

1. Check file permissions: ensure the kubeconfig file and its directory are writable by the running user (ls -l ~/.kube/config; chmod/chown as needed).
2. Ensure the directory exists (mkdir -p ~/.kube) and HOME is set correctly.
3. In containers/CI, mount the kubeconfig directory as read-write instead of read-only.
4. Check disk space/quota with df if I/O errors persist.

Example fix

// before: kubens unset run in CI with read-only mounted config
// after: ensure writable mount
// docker run -v "$HOME/.kube:/home/user/.kube:rw" ...
// chmod u+w ~/.kube/config

// Shell: ensure the kubeconfig is writable before mutating commands
cfg="${KUBECONFIG:-$HOME/.kube/config}"
mkdir -p "$(dirname "$cfg")"
[ -w "$cfg" ] && [ -w "$(dirname "$cfg")" ] || { echo "kubeconfig not writable: $cfg"; exit 1; }

if err := unsetOp.Run(os.Args, os.Stderr); err != nil {
	if strings.Contains(err.Error(), "failed to save kubeconfig file") {
		fmt.Fprintln(os.Stderr, "Check write permissions on ~/.kube/config and that the filesystem is not read-only.")
	}
	return err
}

When it happens

Trigger: kc.Save() errors after a successful SetNamespace during kubens unset: read-only ~/.kube directory, no write permission on config, ~/.kube missing, or an I/O error on flush.

Common situations: Running as a different user than the kubeconfig owner (root vs user); HOME not set in CI containers so the loader targets an unwritable path; read-only container filesystems; disk quota exceeded.

Understand the failure class

Background: "Permission denied" / "Failed to write" file errors: why a library can't write its files to disk (EACCES, EPERM, ENOSPC) and how to fix them — this error's family across 43 libraries.

Related errors

• failed to save kubeconfig file: %w
• failed to open file %q: %w
• kubeconfig error: %w
• failed to get current context: %w
• failed to read namespace of "%s": %w

AI-assisted analysis of ahmetb/kubectx@12ad6fb22e (2026-09-02). Data as JSON: /api/errors/5952684db68e11cd. Report an issue: GitHub.